"The lead character is a guy called Jack Bauer and he's going to have a really crappy day. It's no more complicated than that.

"Everything is explained. What he has been doing over these last four years is very well articulated. So I think it's a very simple show to watch."

Live Another Day is shot and set in East London where Bauer resurfaces after years spent as a fugitive in Europe.

On the run from his own Government, he returns to prevent an assassination attempt on the President of the United States.

While fictional, 24 has always remained topical and season 9 is no different with military drones, sinister threats from China, and a Wikileaks-style betrayal.

Mary Lynn Rajskub, who revives her role as Bauer's grumpy but most-trusted confidant Chloe O'Brien, said: "One of the things that makes 24 work is that it has both things happening at the same - those heightened, crazy, borderline-unbelievable things that are happening for narrative purposes, alongside real issues that people are talking about."

The real-time drama is fuelled by the impossible moral quandaries that repeatedly face Bauer as he tries to avert disaster.

He regularly resorts to violence to garner vital information and 24 has come in for criticism in the past for its torture scenes, which some have described as excessive.

"The use of torture in the context of our show is a dramatic device," says Sutherland, who is also executive producer on 24.

"I have seven minutes to get this information out of someone otherwise 'this' is going to happen and I'm going to do anything I can to get that information. That's great drama.

"Is it something we are saying should be policy around the world? Obviously not."

Series 9 sees the return of Bauer's former flame Audrey (Kim Raver), and James Heller (William Devane) as the US President.

Self-confessed 24 fan Stephen Fry has also joined the cast as British Prime Minister Trevor Davies, as has The Wire's Gbenga Akinnagbe, who plays field operative Erik Ritter.

The first episodes of 24: Live Another Day were simulcast at 1am on Tuesday in the UK alongside Fox's US East Coast transmission.